US6358234B1 - Absorbent article having deformed hinge and zones of extensibility - Google Patents

Abstract

Absorbent articles such as sanitary napkins, panty liners, adult incontinence devices, and the like, which have flaps are disclosed. The absorbent articles have a deformed hinge that is located between at least a portion of the main body portion of the absorbent article and the flaps, and zones of extensibility for relieving the stresses that develop in the flaps when the flaps are folded down and under a wearer's undergarment.

Description

This is a continuation of application Ser. No. 08/539,915, filed on Oct. 6, 1995, now abandoned, which is a continuation-in-part of the following applications: application Ser. No. 08/253,001, filed Jun. 2, 1994, now U.S. Pat. No. 5,620,430, which is a division of application Ser. No. 08/073,256, filed Jun. 4, 1993, now U.S. Pat. No. 5,389,094, which is a continuation of application Ser. No. 07/469,891, filed Jan. 23, 1990 (now abandoned); application Ser. No. 08/230,454, filed Apr. 21, 1994 (abandoned), which is a division of application Ser. No. 08/042,840, filed Apr. 5, 1993, now U.S. Pat. No. 5,354,400, which is a continuation of application Ser. No. 07/769,607, filed Oct. 1, 1991(now abandoned); application Ser. No. 08/096,121 filed Jul. 22, 1993, now U.S. Pat. No. 5,584,829; and application Ser. No. 08/493,515 filed Jun. 22, 1995, now U.S. Pat. No. 5,891,121.

FIELD OF THE INVENTION

The present invention relates to absorbent articles such as sanitary napkins, panty liners, adult incontinence devices, and the like. Still more particularly, the present invention concerns absorbent articles such as sanitary napkins, and the like having flaps with a deformed hinge and zones of extensibility for relieving the stresses that develop in the flaps when the flaps are folded down and under a wearer's undergarment.

BACKGROUND OF THE INVENTION

Absorbent articles, particularly sanitary napkins, having wings or flaps are disclosed in the patent literature and are available in the marketplace. Sanitary napkins having flaps of the various types are disclosed in U.S. Pat. No. 4,687,478, entitled “Shaped Sanitary Napkin With Flaps”, which issued to Van Tilburg on Aug. 18, 1987, U.S. Pat. No. 4,608,047, entitled “Sanitary Napkin Attachment Means”, which issued to Mattingly on Aug. 26, 1986, U.S. Pat. No. B1 4,589,876, entitled “Sanitary Napkin”, which issued to Van Tilburg on May 20, 1986, U.S. Pat. No. 4,285,343, entitled “Sanitary Napkin”, which issued to McNair on Aug. 25, 1981, U.S. Pat. No. 3,397,697, entitled “Disposable Sanitary Shield For Undergarments”, which issued to Rickard on Aug. 20, 1968, and U.S. Pat. No. 2,787,271, entitled “Sanitary Napkin”, which issued to Clark on Apr. 2, 1957.

A number of variations on the types of flaps described above have been presented in an attempt to solve various problems. U.S. Pat. No. 4,900,320 issued to McCoy on Feb. 13, 1990, discloses a sanitary napkin having flaps affixed at points inward from the longitudinal edge of the napkin. U.S. Pat. No. 4,911,701 issued to Mavinkurve on Mar. 27, 1990, discloses a sanitary napkin having elastic means for providing greater convex shape to the body-facing portion of the central absorbent and for enabling adhesive-free placement of the flaps of the napkin. U.S. Pat. No. 4,940,462 issued to Salerno on Jul. 10, 1990, discloses a sanitary napkin with longitudinally expandable flaps. A sanitary napkin having flaps with stress relief means in the form of a notch or a slit is described in U.S. Pat. No. 4,917,697 which issued to Osborn, III, et al. on Apr. 17, 1990. U.S. Pat. No. 5,389,094 issued to Lavash et al. on Feb. 14, 1995, discloses sanitary napkins (and other types of absorbent articles) having flaps and zones of differential extensibility. Although these latter sanitary napkins work quite well, the search for sanitary napkins that are more cost effective, as well as those which have improved flaps has continued.

SUMMARY OF THE INVENTION

In accordance with the present invention, an absorbent article, such as a sanitary napkin, is provided. The sanitary napkin has flaps with a deformed hinge and zones of extensibility for relieving the stresses that develop in the flaps when the flaps are folded around and under the edges of the crotch of the wearer's panties.

The sanitary napkin has a principal longitudinal centerline and a principal transverse centerline. The sanitary napkin comprises a main body portion and a pair of flaps joined to the main body portion. The main body portion of the sanitary napkin comprises a liquid pervious topsheet, a liquid impervious backsheet joined to the topsheet, an absorbent core positioned between the topsheet and the backsheet. The main body portion has two spaced apart longitudinal edges and two spaced apart transverse end edges.

The flaps are each joined to the main body portion at a juncture. The flaps extend laterally outward from at least a central region of the main body portion beyond the longitudinal side edges of the main body portion. In one preferred embodiment, the flaps are integral extensions of the topsheet and backsheet. The flaps are divided into a front half and a back half by a flap transverse centerline. The flaps each have two corner regions which are located adjacent the area of the ends of the junctures of the flaps with the main body portion. One corner region is located adjacent the area of the juncture in each direction remote from the principal transverse centerline. The sanitary napkin comprises a deformed hinge (or bending zone) located in a region that includes the juncture of the flaps with the main body portion and zones of differential extensibility in the corner regions of the flaps. The deformed hinge provides at least one axis about which the flaps may fold relative to the main body portion. The zones of differential extensibility allow the corner regions to extend outward (preferably in a generally transverse direction) to provide a means for the relief of stresses that develop in the flaps of the sanitary napkin when the sanitary napkin are folded down and under a wearer's undergarments.

In an alternative embodiment, at least a portion of the deformed hinge comprises a portion of the sanitary napkin which has a strainable network formed therein. The strainable network comprises at least two visually distinct regions. The network is configured so that at least one of the regions, the second regions, have a surface-pathlength (dimension measured along the surface) which is greater than that of the other regions, the first regions. The second regions exhibiting the longer surface-pathlength preferably comprise one or more rib-like elements. The first regions with the shorter surface-pathlength are preferably substantially planar. In this embodiment, the portion of the deformed hinge comprising this type of strainable network is preferably located at least in the region of the flap transverse centerline.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a preferred sanitary napkin embodiment of the present invention.

FIG. 2 is a lateral cross-sectional view taken alongline2—2 of FIG.1 through the corner region of one of the flaps of the sanitary napkin.

FIG. 3 is a lateral cross-sectional view taken alongline3—3 of FIG.1 through the center portion of one of the flaps.

FIG. 4 is a perspective view of the crotch portion of a woman's panties with the sanitary napkin shown in FIGS. 1-3 in place therein.

FIG. 5 is a top plan view of a web material having a strainable network of the type used in the deformed hinge of the sanitary napkin shown in FIGS. 1-3, the web material being shown in a substantially untensioned condition.

FIG. 6 is an enlarged segmented perspective illustration of the web material shown in FIG. 5 in which the web material is in a substantially untensioned condition.

FIG. 7 is an enlarged segmented perspective illustration of the web material shown in FIG. 5 in which the web material is subjected to tension in an amount which is sufficient for a substantial portion of the deformations of the web material to enter the plane of applied elongation.

FIG. 8 is an enlarged segmented perspective illustration of the web material shown in FIG. 5 in which the web material is in a condition in which it will exhibit a second stage of resistive forces to elongation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to absorbent articles that are worn in an undergarment, such as sanitary napkins, panty liners, incontinence devices, and the like. More particularly, the present invention relates to absorbent articles having flaps with a deformed hinge and zones of extensibility for relieving the stresses that develop in the flaps when they are folded down and under a wearer's undergarment.

A preferred embodiment of asanitary napkin20 of the present invention is shown in FIG.1. As shown in FIG. 1, thesanitary napkin20 basically comprises an absorbent means (or “main body portion”)22, and twoflaps24. Thesanitary napkin20 has two surfaces, a body-contacting surface or “body surface”20A and agarment surface20B. Thesanitary napkin20 is shown in FIG. 1 as viewed from itsbody surface20A. Thebody surface20A is intended to be worn adjacent to the wearers body. Thegarment surface20B is intended to be placed adjacent to the wearer's undergarments when thesanitary napkin20 is worn.

Thesanitary napkin20 has two centerlines, a principal longitudinal centerline L and a principal transverse centerline T. The term “longitudinal”, as used herein, refers to a line, axis or direction in the plane of thesanitary napkin20 that is generally aligned with (e.g., approximately parallel to) a vertical plane which bisects a standing wearer into left and right body halves when thesanitary napkin20 is worn. The terms “transverse” or “lateral” used herein, are interchangeable, and refer to a line, axis or direction which lies within the plane of thesanitary napkin20 that is generally perpendicular to the longitudinal direction.

FIG. 1 shows that themain body portion22 of thesanitary napkin20 comprises the portion of the sanitary napkin without theflaps24. Themain body portion22 has two spaced apartlongitudinal edges26, two spaced apart transverse or end edges (or “ends”)28, which together form theperiphery30 of the main body portion. Themain body portion22 also has two end regions, which are designatedfirst end region32 andsecond end region34. Acentral region36 is disposed between theend regions32 and34. Theend regions32 and34 extend outwardly in the longitudinal direction from the edges of thecentral region36 about ⅛ to about ⅓ of the length of the main body portion. A detailed description of the characteristics of a central region and two end regions for a sanitary napkin is contained in U.S. Pat. No. 4,690,680 issued to Higgins on Sep. 1, 1987.

Themain body portion22 of thesanitary napkin20 can be of any thickness, including relatively thick, intermediate thickness, relatively thin, or even very thin (or “ultra thin”). An “ultra-thin”sanitary napkin20 as described in U.S. Pat. Nos. 4,950,264 and 5,009,653 issued to Osborn preferably has a caliper of less than about 3 millimeters. The embodiment of thesanitary napkin20 shown in the drawings is intended to be an example of a sanitary napkin of an intermediate thickness. Themain body portion22 of thesanitary napkin20 may also be relatively flexible, so that it is comfortable for the wearer. It should be understood that the sanitary napkin shown is merely one embodiment, and that the present invention is not limited to absorbent articles of the type or having the specific configurations shown in the drawings.

FIG. 2 shows the individual components of themain body portion22 of thesanitary napkin20 of the present invention. Themain body portion22 of the sanitary napkin preferably comprises at least three primary components. These include a liquidpervious topsheet38, a liquidimpervious backsheet40, and anabsorbent core42 positioned between thetopsheet38 and thebacksheet40. The topsheet, the backsheet, and the absorbent core may be assembled in a variety of configurations known in the art (including layered or “sandwich” configurations and wrapped or “tube” configurations).

Suitable materials for the components of themain body portion22, and some of the various configurations in which such components can be assembled are described generally in U.S. Pat. No. 4,321,924, “Bordered Disposable Absorbent Article” issued to Ahr on Mar. 30, 1982; U.S. Pat. No. 4,425,130, “Compound Sanitary Napkin” issued to DesMarais on Jan. 10, 1984; U.S. Pat. No. 4,950,264, “Thin, Flexible Sanitary Napkin” issued to Osborn on Aug. 21, 1990: U.S. Pat. No. 5,308,346, “Elasticized Sanitary Napkin” issued to Sneller, et al. on May 3, 1994; and U.S. Pat. No. 5,389,094 “Absorbent Article Having Flaps and Zones of Differential Extensibility” issued to Lavash, et al. on Feb. 14, 1995. Themain body portion22 of the sanitary napkin may also be comprised of one or more extensible components such as those sanitary napkins, and the like described in U.S. patent application Ser. Nos. 07/915,133 and 07/915,284, both filed Jul. 23, 1992, in the name of Osborn, et al. (PCT Publication Nos. WO 93/01785 and 93/01786, both published Feb. 4, 1993).

FIGS. 1-3 show a preferred embodiment of thesanitary napkin20 assembled in a sandwich construction in which thetopsheet38 and thebacksheet40 have length and width dimensions generally larger than those of theabsorbent core42. Thetopsheet38 and thebacksheet40 extend beyond the edges of theabsorbent core42 to form portions of theperiphery30. Thetopsheet38 is preferably joined to the body-facing side of theabsorbent core42 and thebacksheet40 is preferably joined to the garment-facing side of the absorbent core. Thetopsheet38 andbacksheet40 can be joined to the absorbent core in any suitable manner known in the art for this purpose, such as by an open pattern of adhesives. The portions of thetopsheet38 andbacksheet40 that extend beyond the edges of the absorbent core are preferably also joined to each other. Thetopsheet38 andbacksheet40 can be joined in any suitable manner known in the art for this purpose. Preferably, in the embodiment shown, these portions of thetopsheet38 andbacksheet40 are joined using adhesives over substantially the entire portions that extend beyond the edges of theabsorbent core42, and a crimp seal at the end edges28 of the main body portion where thetopsheet38 andbacksheet40 are densified by the application of pressure or heat and pressure.

Thesanitary napkin20 shown in FIGS. 1-3, as discussed above, also comprises a pair offlaps24 that are joined to themain body portion22. Theflaps24 extend laterally outward beyond the longitudinal side edges22 of themain body portion22 from theirproximal edges44 to their distal edges (or “free end”)46. Theflaps24 extend outward from at least thecentral region36 of themain body portion22. As shown in FIG. 1, eachflap24 is divided into afront half48, and aback half50 by a flap transverse centerline T₁. The flap transverse centerline T₁may coincide with the principal transverse centerline T of the sanitary napkin, but this is not absolutely required.

Theflaps24 can be joined to th emain body portion22 in any suitable manner. The term “joined”, as used herein, encompasses configurations in which an element is directly s e cured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e., one element is essentially part of the other element. Preferably, in the embodiment shown in FIGS. 1-3, theflaps24 are integral with the main body portion22 (that is, theflaps24 comprise integral extensions of thetopsheet38 and backsheet40).

In other alternative embodiments, theflaps24 can comprise one or more separate components that are joined to the garment-facing side of themain body portion22. Preferably, in such a case, theflaps24 each comprise a separate component that is joined to the garment-facing side of themain body portion22. In such alternative embodiments, theflaps24 are preferably otherwise unattached to the garment-facing side of themain body portion22 of thesanitary napkin20 between the points where they are attached to the main body portion and the longitudinal side edges26 of the main body portion. Theflaps24 in these latter embodiments can be joined to the garment-facing side of themain body portion22 by any suitable attachment mechanism. Suitable attachment mechanisms include, but are not limited to adhesives, and the like.

Theflaps24 are each joined to (or associated with)main body portion22 along a juncture. This is typically a longitudinally-oriented (or “longitudinal”) juncture, such as lines ofjuncture52. As used herein, the terms “juncture” (or “line of juncture”) refer to regions where theflaps24 extend from or are join ed to themain body portion22. These regions can be any of various curved or straight lines, but they are not limited to lines. Thus, these regions can comprise flanges, strips, intermittent lines, and the like. The line ofjuncture52 in the embodiment illustrated in FIG. 1 can be considered to be defined by concave inwardly-oriented regions or lines if theproximal edges44 of theflaps24 are considered to coincide with the inwardmost boundary of the hinge54 (described below).

Thesanitary napkin20 shown in FIGS. 1-3 preferably has a deformed region that forms ahinge54 between themain body portion22 and at least a portion of theflaps24. Thesanitary napkin20 preferably also has at least one zone of extensibility (or “zone of differential extensibility”)56 for relieving the stresses on theflaps24 when they are folded around a panty crotch. These are each described below.

In the sanitary napkin shown in FIGS. 1-3, thehinge54 comprises a generally longitudinally-oriented, mechanically-deformed region. Thehinge54 provides a region of thesanitary napkin20 with increased flexibility to create preferred bending axes for theflaps24 to bend or fold about. Thehinge54 is preferably located in a region along thejuncture52 of theflaps24 with themain body portion22. Thehinge54, however, does not have to coincide exactly with thejuncture52 of theflaps24 with themain body portion22. Thehinge54 can be located laterally inboard of thejuncture52 of the flaps with themain body portion22, on the juncture, laterally outboard of the juncture, or any combination of the foregoing. If thehinge54 is located laterally inboard of the juncture or on the juncture, thehinge54 may be considered to be formed in at least part of the main body portion22 (and, in the latter case, also in part of the flaps24).

Thehinge54 can extend along theentire juncture52 of the flaps with the main body portion, or along only a portion thereof If thehinge54 is only provided along a portion of thejuncture52, it is preferably provided in the region of thesanitary napkin20 surrounding and including the flap transverse centerline. Thehinge54 can be in many possible configurations. Thehinge54 can comprise a continuous region, or a plurality of spaced apart intermittent regions. Thehinge54 can be rectilinear, curvilinear, or it can comprise portions that are rectilinear and portions that are curvilinear. Thehinge54 has a laterally inwardmost, or proximal,boundary54A and an outermost, or distal,boundary54B. In the embodiment shown in FIGS. 1-3, at least theinwardmost boundary54A of thehinge54 is preferably concave inwardly relative to the distal edge of theflaps54.

Thehinge54 can be formed in any suitable manner that provides the desired region of the sanitary napkin with increased flexibility. Preferably, thehinge54 is formed by mechanically deforming the desired regions of the sanitary napkin. It has been found that many processes suitable for providing regions of the sanitary napkin with extensibility are particularly suitable for providing regions of thesanitary napkin20 selected for thehinge54 with enhanced flexibility.

Thehinge54 can, for instance, be formed by a process which has been described as pre-corrugating (or “ring rolling”). Suitable methods for ring rolling are described in U.S. Pat. No. 4,107,364 issued to Sisson on Aug. 15, 1978, U.S. Pat. No. 4,834,741 issued to Sabee on May 30, 1989, U.S. Pat. NO. 5,143,679 issued to Gerald M. Weber, et al. on Sep. 1, 1992, U.S. Pat. No. 5,156,793 issued to Kenneth B. Buell, et al. on Oct. 20, 1992, and U.S. Pat. No. 5,167,897 issued to Gerald M. Weber, et al. on Dec. 1, 1992.

Alternatively, as shown in FIG. 1 for purposes of illustration, thehinge54 is provided by forming a strainable network in the region along thejuncture52 of theflaps24 with themain body portion22. The process for forming a strainable network region, and structures formed thereby are described in greater detail below in conjunction with FIGS. 5-8. This technology is further described in allowed U.S. Pat. No. 5,518,801 issued to Chappell, et al. on May 21, 1996 (PCT Publication No. WO 95/03765, published Feb. 9, 1995).

These structures (ring rolled structures and materials with strainable network regions formed therein) are especially preferred for thehinge54 because the alternating ridges and valleys can form a plurality of flexible bending axes for theflaps24. These types of structures also provide thehinge54 with a degree of extensibility. The extensibility allows the portions of theflaps24 in thehinge region54 to expand slightly in the transverse direction to better fold around the curved sides of the wearer's panty crotch. Providing thehinge54 by forming strainable network regions in the sanitary napkin may also be preferred when it is desired to provide the formed regions with slightly more integrity so theflaps24 will be less likely to droop excessively at thehinge54 because the unformed first regions or less extensible bands64 (described below) of the strainable network will serve like “beams” that tend to provide theflaps24 with slightly more structural rigidity and better appearance.

The process of forming a strainable network is preferred for providing thesanitary napkin20 with ahinge54 because (like ring rolling) such an operation can be readily adapted for use in high speed manufacturing operations. Further, the process of forming a strainable network in a material is highly preferred because it can be adapted to produce a virtually unlimited number of patterns to tailor the configuration and characteristics of thehinge54 and zones ofextensibility56.

Typically, the base material into which the strainable network is formed comprises a single layer of material or laminate of materials, at least one of which is a film. Preferably, in the embodiment shown in FIGS. 1-3, the material that has the stainable network formed therein comprises a laminate formed by an extension of the topsheet and backsheet40 of the sanitary napkin. Thetopsheet38 preferably comprises an apertured formed film made in accordance with U.S. Pat. Nos. 4,342,314, Radel, et al. and 4,463,045, Ahr, et al. which is marketed on sanitary napkins as DRI-WEAVE topsheet by The Procter & Gamble Company. Thebacksheet40 preferably comprises a polyethylene film. The two components are preferably laminated together by adhesives.

The characteristics of thestrainable network62 in thehinge54 of the sanitary napkin shown in FIGS. 1-3 will be discussed with reference to FIGS. 5-8. FIGS. 5-8 are enlarged views of a simplified version of aweb material60 having astrainable network62 formed therein. The tern “strainable network”, as used herein, refers to an interconnected and interrelated group of regions which are able to be extended to some useful degree in a predetermined direction. FIGS. 5 and 6 show theweb material60 in an untensioned condition. Thestrainable network62 comprises at least two distinct and dissimilar regions which are designated asfirst region64 andsecond region66.

In the simplified embodiment shown in FIGS. 5 and 6, theweb material60 includes a plurality offirst regions64 and a plurality ofsecond regions66. As shown in FIGS. 5 and 6, thefirst regions64 are substantially planar regions. That is, the material within thefirst region64 is in substantially the same condition before and after the formation step undergone byweb material60. Thesecond regions66 include a plurality of continuous, interconnected, rib-like deformations74 which extend alternately beyond the plane of both the first and second surfaces (64A and64B, respectively) of thefirst region64. In other embodiments, thedeformations74 may extend beyond the plane of only one of the first64A or the second64B surfaces of thefirst region64.

FIG. 5 shows that theweb material60 having thestrainable network62 formed therein has a longitudinal centerline (or axis),1, and a lateral centerline (or axis), t. In the sanitary napkin embodiment shown in FIG. 1, the longitudinal centerline,1, of thestrainable network62 is shown as being rectilinear and generally oriented in the transverse direction. However, the longitudinal centerline,1, is not limited to such a configuration and orientation. The longitudinal centerline,1, can be rectilinear, curvilinear, or partially rectilinear and partially curvilinear. The longitudinal centerline,1, of thestrainable network62 can also be oriented in other directions, if desired.

FIG. 5 shows that thefirst regions64 of thestrainable network62 have afirst axis68 and asecond axis69, wherein thefirst axis68 is preferably longer than thesecond axis69. In the simplified embodiment shown, thefirst axis68 of thefirst region64 is substantially parallel to the longitudinal axis,1, of theweb material60 while thesecond axis69 is substantially parallel to the transverse axis, t, of theweb material60. Thesecond regions66 of thestrainable network62 also have afirst axis70 and asecond axis71. Thefirst axis70 of thesecond region66 is substantially parallel to the longitudinal axis1 of theweb material60, while thesecond axis71 is substantially parallel to the transverse axis1 of theweb material60. In the version of the web material shown in FIGS. 5 and 6, thefirst regions64 and thesecond regions66 are substantially linear, extending continuously in a direction substantially parallel to the longitudinal axis1 of the strainable web material. In other embodiments, thesecond regions66 can be curvilinear, or partially rectilinear and partially curvilinear.

While the enhanced flexibility of the strainable network is of primary interest in forming thehinge54, the strainable network also provides portions of theflaps24 with a degree of extensibility. FIGS. 6-8 show the manner in which theweb material60 with astrainable network62 formed therein may exhibit at least two significantly different stages of controlled resistive force to elongation when subjected to an applied elongation in a direction parallel to a predetermined axis. Thestrainable network62 exhibits first resistive forces to the applied elongation (which develop between the stage shown in FIG.6 and the stage shown in FIG.7). The first resistive forces occur until the elongation of the web is sufficient to cause a substantial portion of thesecond regions66 to enter the plane of applied elongation, as shown in FIG.7. After theweb material60 reaches the stage shown in FIG. 7, it exhibits second resistive forces to further elongation (as illustrated by FIG.8). Typically, when used in regions of thesanitary napkin20 described herein, the web material will be within the firs t stage of resistance to elongation so the various portions of thestrainable network62 will only extend to the stage shown in FIG.7 and adjust so as to relax back to the stage shown in FIG.6.

Thehinge54 is created by forming thestrainable network62 into the desired portion of thesanitary napkin20. As used herein, the term “forming” refers to the creation of a desired structure or geometry upon a web material or laminate that will substantially retain the desired structure or geometry when it is not subjected to any externally applied elongations or forces. Suitable methods for forming a strainable network into a web material include, but are not limited to embossing by mating plates or rolls, thermoforming, high pressure hydraulic forming, and casting.

The portion of thesanitary napkin20 into which thestrainable network62 is formed can comprise a base material (or laminate) that has a relatively low extensibility under the forces that the sanitary napkin is normally subjected to when worn. When thestrainable network62 is formed therein, however, the base material can be made extensible under pre-selected forces such as those that the sanitary napkin is normally subjected to when worn.

The depth and number ofdeformations74 in thestrainable network62 can be varied to control the applied force or elongation required to extend the material in thehinge regions54 of thesanitary napkin20. In one embodiment, thedeformations74 may be formed by two rigid plates having a pattern of meshing teeth. The outer dimensions of the pattern of teeth covers a surface area of the plates that is about 7.9″ by 1.6″ (20 cm by 4 cm) for each flap. On one surface of each plate are a series of teeth which are substantially triangular in cross section and taper to a radiused vertex. The teeth in this embodiment preferably have a height of 3.175 mm, and are evenly spaced with the centerlines of the teeth spaced apart at 0.075″ (1.9 mm) increments. On the “toothed” side of one plate, a series of grooves (preferably three grooves to construct the embodiment shown in FIG. 1) are cut which are parallel to each other and perpendicular to the evenly spaced teeth. These grooves correspond to the undeformed regions of the base material.

The preferred base material is placed between the plates in a hydraulic press having platens larger than the plates to evenly distribute pressure. The plates are compressed so that the teeth only partially engage (or mesh). Preferably, the plates are moved so that the teeth on the opposite plates are pressed toward each other about 80% of the distance toward full engagement (the point where the teeth would otherwise touch). Typically, in order to do this, when the base material comprises a laminate of apertured formed film and polyethylene backsheet material laminated together by adhesives that is described in conjunction with the embodiment shown in FIGS. 1-3, the plates will be compressed under a load of between about 25-70 psi. (about 1,750-4,900 g/cm2). The formed web material is then removed from between the plates. In the embodiment shown in FIGS. 1-3, the formed web material is provided with about 75% extensibility. The available stretch or elongation is increased if for a given number of deformations, the height or degree of deformation imparted to the web material is increased. Similarly, the available stretch or elongation is increased if for a given height or degree of deformation, the number or frequency of deformations is increased. The mating plates can be configured to create any of the patterns for thehinge54 on the sanitary napkins shown in the drawings.

The sanitary napkin also has zones ofextensibility56 for relieving the stresses that develop in the flaps when they are folded down and under a wearer's undergarment. The terms “zone of extensiblity” or “zone of differential extensibility”, as used herein, refer to a portion of thesanitary napkin20 which is capable of extending (and are preferably capable of extending a greater amount than surrounding portions of the sanitary napkin20). Thesanitary napkin20 preferably has at least one zone ofextensibility56 for eachflap24, and more preferably has four zones ofextensibility56, one in each quarter of thesanitary napkin20. Since the zones ofdifferential extensibility50 relieve stresses in the flaps, they may be referred to herein as a type of “stress relief means”.

The zones ofextensibility56 can be extensible in any desired direction, or in more than one direction. However, the zones ofextensibility56 are preferably primarily extensible generally outward in the transverse direction. This is generally in the direction of the arrows shown in FIG.1. As used herein, “generally in the transverse direction” means that the extensibility has a transverse component. All of the extension, however, need not be exactly parallel to the principal transverse centerline of the sanitary napkin. The extensibility, however, is preferably oriented more in the transverse direction than in the longitudinal direction.

The zones ofextensibility56 can comprise any structure capable of extending in the transverse direction (or in any other direction desired). The extensibility referred to herein, however, should be elasticless. That is, it should be accomplished without the use of separate elastic pieces, strands, or materials to contract one or more portions of the sanitary napkin. The zones of extensibility must also be accomplished without slitting or notching portions of the sanitary napkin that cover the wearer's undergarments. The zones ofextensibility56, therefore, comprise continuous material. This will have the advantage that exudates will not be able to travel through the slits or notches to soil the wearer's undergarments.

Suitable structures for the zones ofextensibility56 include, but are not limited to zones of material that are mechanically strained, corrugated, “ring rolled”, formed with a strainable network therein, formed with a network of corrugations without any less extensible bands therein, folded, pleated, or joined along a curved juncture. These structures (although shown only as being part of the flaps24), can comprise portions of themain body portion22, portions of theflaps24, or both. They can be integral parts of these components of the sanitary napkin, or separate elements, such as pieces of material, joined to the sanitary napkin. Suitable structures for the zones of extensibility are described in greater detail in U.S. Pat. No. 5,389,094 issued to Lavash, et al. on Feb. 14, 1995.

In the embodiment shown in FIG. 1, the zones ofextensibility56 can either comprise ring rolled regions of the flaps or a network of corrugations without, any less extensible bands therein. In either case, the zones ofextensibility56 preferably have corrugations with ridges that are oriented generally in the longitudinal direction so that the zones of extensibility will be extensible primarily in the transverse direction.

There are many possible arrangements and configurations that the zones ofextensibility56 may have relative to each other and relative to thehinges54. The zones of extensibility56 (or at least portions thereof) are preferably spaced longitudinally away from the flap transverse centerline T1. As shown in FIG. 1, the portions of the zones ofextensibility56 that are spaced laterally furthest outward from thejuncture52 of theflaps24 with themain body portion22 are separated by anintermediate region58. The portions of the zones ofextensibility56 that are closest to thejuncture52 of theflaps24 with themain body portion22 can also be spaced longitudinally away from the flap transverse centerline T1 so that they do not abut each other. Alternatively, these portions of the zones ofextensibility56 can abut each other.

Theintermediate region58 comprises a region of theflap24 that includes the flap transverse centerline T1 and laterally adjacent regions. Theintermediate region58 is preferably stiffer than the regions of the sanitary napkin that comprise thehinge54 and the zones ofextensibility56. This provides theflaps24 with more integrity so that they will be easier for the user to handle. Thus, themain body portion22 of the sanitary napkin is preferably the stiffest portion of the sanitary napkin. Theintermediate region58 is preferably the stiffest portion of theflaps24, and is preferably not as stiff as themain body portion22. Thehinge54 is preferably more flexible than either of those portions of the sanitary napkin.

The zones ofextensibility56 can be spaced away from thehinge54, or be adjacent to thehinge54. Preferably, as shown in FIG. 1, thehinge54 is contiguous (that is, touching or connected throughout in an unbroken sequence) with the zones ofextensibility56. Thehinge54 and the preferred ring rolled zones ofextensibility56 are, thus, portions of a continuous composite deformed region. As shown in FIG.1, thehinge54 gradually transitions into portions of the sanitary napkin that comprise the zones ofextensibility56. The composite deformed region, thus, comprises continuous corrugations having ridges that are generally oriented in the longitudinal direction with a plurality ofinextensible bands64 in the center region adjacent the flap transverse centerline T1.

As shown in FIG. 1, the composite deformed region preferably has a proximal boundary along thejuncture52 of theflaps24 with themain body portion22 that is concave relative to thedistal edges46 of theflaps24. The composite deformed region preferably has a distal boundary that is also concave relative to thedistal edges46 of the flaps. FIG. 1 shows that the distal boundary of the composite deformed region defines the boundary of theintermediate region58 as a generally semi-circular area. Further, as shown in FIG. 1, the radius of curvature of the distal boundary of the composite deformed region is preferably less than the radius of curvature of the proximal edge of the composite deformed region.

Many variations of the embodiments described herein are possible. For example, instead of comprising corrugations with linear ridges that are oriented in the longitudinal direction, the deformations forming these regions can be arranged in the form of a series of concentric concave ridges and valleys that are aligned with the boundaries of these regions. In another example, instead of being a contiguous composite deformed region, thehinge54 and the zones ofextensibility56 may be separate spaced apart structures. Alternatively, thehinge54 and/or the zones ofextensibility56, instead of comprising deformed regions of the sanitary napkin, can comprise some other suitable type of structure that provides the sanitary napkin with the desired properties of increased flexibility and extensibility in these regions. Themain body portion22 of thesanitary napkin20 can also comprise a pair of embossed channels as described in U.S. Pat. No. 5,308,346 issued to Sneller, et al. The features shown and described herein for the various embodiments can also be combined in any other suitable ways to form still more alternative embodiments.

Thegarment surface20B of thesanitary napkin20 may include, and preferably does include, fasteners for attaching the sanitary napkin to the wearer's undergarment. FIG. 1 shows thecentral pad fastener80 which is adapted to secure themain body portion22 of the sanitary napkin to the crotch region of an undergarment. Any types of fasteners known in the art, such as adhesive fasteners and mechanical fasteners can be used. Fasteners comprising adhesives have been found to work well for this purpose, with pressure-sensitive adhesives being preferred. FIG. 1 shows a preferred arrangement which utilizes a pair of spaced apart longitudinally-oriented strips or zones of adhesive80 that are centered about the longituded centerline L.

The outer surface of theflaps24, adjacent thedistal edges46 of the flaps, is preferably provided with aflap adhesive82. Theflap adhesive82 is used to assist in maintaining theflaps24 in position after they are wrapped around the edge of the crotch portion of the panty. Suitable adhesive fasteners are described in greater detail in U.S. Pat. No. 4,917,697. Theflaps24 can be maintained in position by attaching theflaps24 to the undergarment, or to the opposing flap.

The fasteners used with the present invention are not limited to adhesive attachment means. Any type of fastener used in the art can be used for such purpose. For example, thesanitary napkin20 could be secured to the wearer's undergarment by mechanical fasteners, such as VELCRO, or the fasteners described in U.S. Pat. No. 4,946,527 entitled “Pressure-Sensitive Adhesive Fastener and Method of Making the Same” issued to Battrell on Aug. 7, 1990, or U.S. Pat. No. 5,392,498 entitled “Non-Abrasive Skin Friendly Mechanical Fastening System” issued to Goulait, et al. on Feb. 28, 1995. For simplicity, however, the fasteners will be described in terms of adhesive attachment means.

The adhesive attachment means are respectively covered by removable release liners, central pad release liner and flap release liner, both designated84. The pressure-sensitive adhesives should be covered withrelease liners84 to keep the adhesives from sticking to extraneous surfaces prior to use. Suitable release liners are described in U.S. Pat. No. 4,917,697. A particularly preferred release liner which also serves as an individual package for wrapping the sanitary napkin is described in U.S. Pat No. 4,556,146 issued to Swanson, et al. In other embodiments, theflaps24 could be folded and tucked as described in U.S. Pat. No. 5,281,209 issued to Osborn, et al. on Jan. 25, 1994. The adhesive attachment means on such flaps could, instead of being covered with a release liner, be releasably adhered to a release surface provided on some other portion of the sanitary napkin, including the main body portion, or the flaps, or a separate component attached to the main body portion or the flaps.

Thesanitary napkin20 of the present invention is utilized by removing therelease liners84 and placing thesanitary napkin20 in a panty11 as shown in FIG. 4 Themain body portion22 is placed in the crotch portion of the panty with one end of themain body portion22 extending towards the front section of the panty and the other end towards the back section of the panty. Thebacksheet40 is placed in contact with the inner surface of the center of the crotch portion of the panty. The central padadhesive fastener80 maintainsmain body portion22 in position. The distal portions of theflaps24 are folded around the side edges16 of the panty. Theflap adhesives82 secure theflaps24 to the underside of the panty or to the opposing flap.

Other embodiments of the absorbent articles are also possible. For example, in alternative embodiments, instead of being provided with flaps, the absorbent article could be provided with undergarment covering components or (“side wrapping elements”) that have a smaller span than conventionally sized flaps and that do not have to be manipulated by the wearer when placed in the wearer's undergarments. Absorbent articles having side wrapping elements are described in U.S. patent application Ser. No. 08/096,121 entitled “Absorbent Articles Having Panty Covering Components That Naturally Wrap the Sides of Panties” filed Jul. 22, 1993, in the name of Lavash, et al. (PCT Publication No. WO 94/02096, published Feb. 3, 1994); U.S. patent application Ser. No. 08/124,180 entitled “Absorbent Articles Having Panty Covering Components Comprising Extensible Web Materials Which Exhibit Elastic-Like Behavior” filed Sep. 17, 1993, in the name of Mansfield, et al. (PCT Publication No. WO 95/07675, published Mar. 23, 1995); and U.S. patent application Ser. No. 08/277,733 entitled “Absorbent Articles Having Undergarment Covering Components With Zones of Extensibility” filed Jul. 20, 1994 in the name of Weinberger, et al. (PCT Publication No. WO 95/03025, published Feb. 2, 1995).

The disclosures of all patents, patent applications (and any patents which issue thereon, as well as any corresponding published foreign patent applications), and publications mentioned throughout this patent application are hereby incorporated by reference herein. It is expressly not admitted, however, that any of the documents incorporated by reference herein teach or disclose the present invention. It is also expressly not admitted that any of the commercially available materials or products described herein teach or disclose the present invention.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention.

Claims (4)

What is claimed is:

1. An absorbent article for wearing in a crotch region of an undergarment, said crotch region having a pair of side edges, said absorbent article having a liquid pervious body-facing side, a liquid impervious garment side, a principal longitudinal centerline extending in a longitudinal direction, and a principal transverse centerline extending in a transverse direction, said absorbent article comprising:

a main body portion having a central region, two spaced apart longitudinal side edges and two spaced apart end edges, said main body portion comprising an absorbent core positioned between said body-facing side and said garment side;

a pair of flaps for folding around the side edges of the crotch region of undergarment, said flaps being joined to said main body portion, each flap extending laterally outward along one of the longitudinal side edges to a distal edge, said flaps each having a flap transverse centerline that passes through said central region of said main body portion;

a deformed region comprising a portion of said absorbent article that has planar portions and at least some portions that are displaced in a direction perpendicular to said planar portions, wherein said deformed region is substantially free of overlapping portions, and said deformed region forms a hinge between said main body portion and said flaps; and

at least one zone of extensibility comprising at least a portion of at least one of said flaps, wherein at least a portion of said zone of extensibility is spaced longitudinally away from said flap transverse centerline.

2. The absorbent article ofclaim 1 wherein a portion of said flaps outboard of said distal boundary of said composite region is a generally semi-circular area that is substantially planar and is stiffer than said composite region.

3. The absorbent article ofclaim 2 wherein said generally semi-circular portion of said flaps has a fastener thereon.

4. The absorbent article ofclaim 1 wherein said hinge has a pre-formed distal boundary spaced apart from said proximal boundary which is also concave relative to the distal edge of said flap.

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